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Tuatara Breeding Programme – Country Side Magazine
By Lindsay C Hazley

The tuatara (Sphenodon punctatus) is endemic to New Zealand surviving only on 31 off-shore islands. From the order Sphenodontic, tuatara have continued to survive here since New Zealand separated from Gondwanaland some 80 million years ago. The tuatara's ancestry dates back 225 million years, unchanged for the last 80 million years. This makes it of unique biological significance. Physiologically they are extreme among reptiles in a number of traits, including longevity, providing an opportunity to study an often called "living fossil".

As Tuatara Curator at the Southland Museum and Art Gallery, I took on the challenge 20 years ago to be the first to breed tuatara in captivity (starting with one pair). Tuatara at that time had a poor life expectancy in captivity, mainly attributable to the isolation of tuatara to off-shore islands where access and study was very difficult, resulting in insufficient information on reproduction, physiology and habitat requirements.

The Southland Museum's tuatara programme was one of the first to have captive-bred tuatara and continued with successful breeding to achieve the world's only regular captive breeding, within the animals physiological possibly, one every two years. My long term study of tuatara has enabled me to pioneer many of the innovations essential for the successful keeping of tuatara in captivity.

To date no captive-bred tuatara have themselves reached maturity and reproduced. My oldest off-spring are 10 years old and may become sexually mature within the next two years.

Problem Solving

The first problem to solve was the tuatara's territorial assertions and then the realisation of the requirement of more than one male to achieve certain breeding. The New Zealand Internal Affairs Department distribution policy was one pair only to an institution.

I was convinced that the presence of a second male would trigger an urgency as to whose genetic line would continue! My persistence for additional tuatara was rewarded in 1982 with another male and female to join the existing pair, Henry and Mildred (Henry estimated to be around 100 years old and Mildred to be in her late 30's).

The new arrivals were named Albert and Lucy and the first successful breeding resulted in 1984 after improvements (covering most of the roof with a clear propagating plastic and heat lamps outside each tuatara burrow) to control the climate in the enclosure. The air temperature was not allowed to go below 3 Celsius compared with the -5C previously experienced in their outdoor enclosure over the winter period.

The tuatara have distinctive seasonal behaviour, mating in February/March and egg laying October/November/December. The egg take from 6-10 months to hatch depending on soil temperature.

Although a male tuatara has no copulatory organ mating is still an intensive ritual, courting the receptive female with spines erect; throat puffed out, circling her in a proud, stiff-legged walk. Copulation itself may occupy an hour, involving the male climbing over the female from behind, entwining his tail under hers, bringing their cloacae into apposition.

To identify the female's reproductive condition I X-ray them in September. Eggs which are ready to be laid show up well and can be counted (average 10-18 eggs per female). The chances of the enclosure's soil condition (temperature and moisture) being suitable for incubation is most unlikely. In the wild, normally eggs are usually laid in a tunnelled out nest and abandoned.

My first attempt to recover the buried eggs was the placement of the egg carrying females in separate holding boxes and 300mm of soil. This worked for one female, successfully recovering all her eggs, but the second female only laid some of her eggs, retaining seven, which could have resulted in her death if I hadn't induced her with an injection of Oxytocin. These last eggs were laid within four hours of induction. None of the eggs were fertile and all decomposed within two weeks of being laid.

For the 1986 egg laying I left the females to lay their eggs in the enclosure keeping a regular watch to ensure the recovery of the eggs if necessary. Both females chose to lay their eggs outside their burrow under the overhead heat lamp in shallow nests. The soil temperatures seemed to be warm enough so I left the eggs in the ground. Four months later on inspecting the eggs I discovered they were being eaten by juvenile millipeads (Diplopoda). I removed the eggs to sterilised soil in containers in my office. The moisture content was just estimated to a degree that the soil looked moist but not muddy. At this time no known reference to the ideal incubation regimes was available.

The eggs continued to develop and increase in size and weight to 18 grams. Tuatara eggs have a soft, parchment-like shell. Finally, after fear of losing all the eggs, I decreased the moisture content in the soil and the last six eggs hatched having decreased in weight to 14 grams.

Statistics later became available of field work carried out by University researches on the tuatara-inhabitated Stephens Island, that tuatara egg weights do not exceed 13 grams.

The 1988 egg retrieval was much more scientific. The females were induced to lay their eggs and the weights of the medium (Vermiculite instead of soil), moisture and egg growth were all recorded.

 Initially the moisture content chosen was 50% but within a few hours the eggs started to show denting, indicating a loss of moisture. Moisture was added to the medium until the eggs regained their natural shape with no dents. Moisture finally was 80%.

Eggs were removed weekly and water loss through evaporation was replaced back into the medium maintaining a constant moisture content. The eggs were all numbered and marked top side to ensure they were not rotated which could result in the death of the embryo.

Within two weeks Mildred's eggs all collapsed and decomposed, indicating they were not fertile. After 31 weeks incubation at 17-26C, seven of Lucy's eggs hatched from the 11 originally laid. In the last two weeks prior to hatching, the eggs reached 14 grams in weight. To avoid loss, the moisture content was lowered to 60%.

I have since had two further clutches of eggs hatch. The last in 1991 with 100% success – 10 hatching.

The mortality rate of the first hatchings was 50% in the first three/five years and the future was not looking good for captive rearing of baby tuatara. The main cause of death was a problem known as "Rubber Jaw" – the non-formation of the lower jaw associated with a chronic calcium deficiency. The babies would reach the stage where they could not eat or hold food in their mouth and as a consequence became run down in condition, eventually resulting in death.

Preventative treatment was the addition of vitamin supplements to their insect diet. (Insects dusted with Calcipup). Muscle seizures attributed to calcium deficiencies were treated with a calcium injection, but the rubber jaw has been incurable. Having no physiological or histopathological data on tuatara for comparison to determine abnormalities, diagnosis was difficult, but the problem indicated that the parathyroid gland was not functioning.

At present I am experimenting with the addition of high frequency ultra violet light which they do not receive in artificial enclosure. I am trying to establish whether or not the extra UV increases calcium absorption with the epidermal production of vitamin D. A starting possibility is that the tuatara's pineal eye/gland is stimulated by high frequency UV to establish circadian rhythm of the parathyroid gland. I attribute the present success of the hatchlings survival to the additional UV light but it will take two/four years to determine which is the responsible factor. At the moment pineal stimulation is looking promising.

Southland Museum and Art Gallery, which is open to visitors 364 days per year, now has a population of over 30 tuatara – the world's best display of tuatara.

E-mail: info@southlandmuseum.co.nz

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